Antifungal susceptibility

Question 1

Current options for treating fungal infection include drugs primarily from four classes:

Answer 1

 Polyene
 Azole
 Echinocandin
 Allylamine

Question 2

 The primary antifungal agent.

Answer 2

Amphotericin B (AMB), a polyene

Question 3

 This agent has a broad spectrum of activity in addition to fungicidal activity. Not only is this agent lethal to fungi, but it is also toxic to patients.

Answer 3

Amphotericin B (AMB), a polyene

Question 4

Patients treated with ____ can experience many adverse side effects, including infusion-related reactions (fever, rigor, myalgia, and arthralgia) and renal impairment.

Answer 4

AMB

Question 5

It remains the drug of choice for most life-threatening fungal disease.

Answer 5

AMB

Question 6

resistance to AMB has been documented with _____ and _____, and in about ______ isolates.

Answer 6

S. boydii
P. lilacinum
6% of Candida lusitaniae

Question 7

 The class that has provided the largest number of agents

Answer 7

Azoles

Question 8

they exhibit reasonable activity against fungi while causing fewer side effects.

Answer 8

azoles

Question 9

The most noteworthy compounds in the Azoles class includes:

Answer 9

	Fluconazole (FLU)
	Itraconazole (ITR)
	Isavuconazole (ISA)
	Posaconazole (POS) 
	Voriconazole (VOR)

Question 10

It is the leading agent for treating yeast infections but has limited to no activity against molds.

Answer 10

Fluconazole (FLU)

Question 11

It is widely used by many practitioners to treat all types of infections, including vaginitis and thrush.

Answer 11

FLU

Question 12

Fluconazole (FLU) overuse or misuse has resulted in the development of resistance, most notably with ______.

Answer 12

C. glabrata

Question 13

It has been useful for treating aspergilli and phaeoid fungi infections

Answer 13

Itraconazole (ITR)

Question 14

shown improved activity against the aspergilli, in addition to several emerging pathogens.
but it lacks activity against Mucorales.

Answer 14

Voriconazole (VOR)

Question 15

______ are the newest azoles and have perhaps the best activity against most fungal species.

Answer 15

ISA and POS

Question 16

Echinocadins (2):

Answer 16

Caspofungin (CAS)

Anidulafungin and Micafungin

Question 17

 This class targets cell wall synthesis which makes it an attractive option for treating fungi that have developed resistance to other agents.

Answer 17

Caspofungin (CAS)

Question 18

Under the class of echinocadins, it is lethal for yeast and, although effective against the aspergilli, is not generally lethal

Answer 18

Caspofungin (CAS)

Question 19

These two antifungals tend to have lower minimal inhibitory concentrations (MICs) compared with CAS.

Answer 19

Anidulafungin and Micafungin

Question 20

Allylamines (2):

Answer 20

Terbinafine

Naftifine

Question 21

It is given orally and is active against several groups of fungi, including the dermatophytes and phaeoid fungi

Answer 21

 Terbinafine

Question 22

used only topically

Answer 22

 Naftifine

Question 23

These compounds (allylamines) interfere with the synthesis of ______, a principal sterol in the plasma membrane of many fungi.

Answer 23

ergosterol

Question 24

Fungal diseases that the drug is used to treat

Question 25

The Clinical and Laboratory Standards Institute (CLSI) in the United States has published four methods for antifungal susceptibility testing:

Answer 25

M27-A3 M38-A2 M44-A2 M51-A

Question 26

for yeast testing

Answer 26

 M27-A3

Question 27

for mold testing

Answer 27

 M38-A2

Question 28

for disk diffusion testing for yeasts

Answer 28

M44-A2

Question 29

for disk diffusion testing for molds

Answer 29

M51-A

Question 30

The most recent methods, ____and _____, were developed as cost-effective procedures that could easily be incorporated into busy microbiology laboratories that routinely perform this type of antimicrobial testing for bacteria.

Answer 30

M44-A2 | M51-A

Question 31

used eliminating the need for multiple media to perform antimicrobial susceptibility testing

Answer 31

Mueller-Hinton agar

Question 32

The FDA has approved a:

Answer 32

Microtiter method - Trek Diagnostic Systems Diffusion method – Etest

Question 33

The largest barrier to widespread antifungal testing is the ______ for most of the agents.

Answer 33

lack of established breakpoints

Question 34

Breakpoints are now species specific by drug, with results placing the organism categorically in the same manner as bacteria. These categories are:

Answer 34

S (susceptible) I (intermediate) R (resistant)

Question 35

The ____ and _____ are categorized as S, SDD (susceptible, dose dependent), and R.

Answer 35

azoles FLU | VOR

Question 36

The azoles FLU and VOR are categorized as _______

Answer 36

S, SDD (susceptible, dose dependent), and R.

Question 37

The _____ category indicates isolates that may be considered susceptible when highdose therapy, as opposed to standard therapy, is used.

Answer 37

SDD

Question 38

It is an end point that can be used to evaluate a given MIC when clinical breakpoints are not available.

Answer 38

Epidemiologic Cutoff Values (ECVs)

Question 39

ECVs does not indicate susceptible or resistant strains but, rather, wild-type and non–wild-type strains, where ______ may harbor mechanisms of antifungal resistance.

Answer 39

non–wild-type strains

Question 40

Those strains with an MIC above the ECV have potentially acquired _______

Answer 40

mechanisms of resistance.

Question 41

All specimens for mycology should be transported and processed ______. Because many pathogenic fungi ____, any delay in processing compromises specimen quality and decreases the probability of isolating the causative agent as a result of overgrowth by contaminants.

Answer 41

ASAP | grow slowly

Question 42

Most common specimens are:

Answer 42

``` respiratory secretions hair skin nails tissue blood bone marrow CSF. ```

Question 43

______ submitted for dermatophyte culture are generally contaminated with bacteria, rapidly growing fungi, or both. With these types of specimens, primary isolation medium should contain ______

Answer 43

Hair, skin, or nails | antimicrobial agents

Question 44

Hair The ______ emits ultraviolet light of wavelength greater than ____ and can be useful in identifying infected hairs.

Answer 44

Wood lamp | 365 nm

Question 45

Hairs infected with fungi such as ______ fluoresce when light from the Wood lamp is focused on the scalp.

Answer 45

Microsporum audouinii

Question 46

______ should be used to pull affected hair.

Answer 46

Sterile forceps

Question 47

Hairs are placed directly into a ____. A few pieces of hair are inoculated onto fungal medium and incubated at _____.

Answer 47

sterile Petri dish | 22° to 30°C

Question 48

Skin Skin must be cleaned with _____ before sampling. Skin samples are scaped from the _____ of a surface lesion. A ______ is prepared with some of the scrapings; the KOH breaks down tissue, making it easier to view fungal hyphae.

Answer 48

70% isopropyl alcohol outer edge KOH wet mount

Question 49

Nail Nails are cleaned with____ before the surface is scraped. Nail specimens may be submitted as _____ and occasionally as a complete nail. ______are necessary to prepare a KOH preparation and inoculate media. ____ are used to cut complete nails into small thin strips, which are used to inoculate media

Answer 49

70% isopropyl alcohol scrapings or cuttings Deeper scrapings Sterile scissors

Question 50

Blood and Bone Marrow Blood from septicemic patients can harbor known pathogenic and opportunistic fungi, the most common being _____ The lysis centrifugation system, the ______ (Wampole, Cranbury, NJ), is the most sensitive method for the recovery of molds and dimorphic fungi. However, this method to has a high contamination rate.

Answer 50

Candida spp. | Isolator tube

Question 51

Automated and continuous monitoring blood culture systems have media designed for the recovery of fungi.

Question 52

Studies indicate _____ of blood from adults divided among two bottles and a dilution of ______

Answer 52

20 to 30 mL | 5- to 10-fold is ideal.

Question 53

_____ specimens should be plated directly onto media at the bedside; use of blood culture bottles is not recommended

Answer 53

Heparinized bone marrow

Question 54

____ and _____body fluids should be concentrated by centrifugation before inoculation.

Answer 54

CSF and other sterile

Question 55

Cerebrospinal Fluid One drop of the concentrate is used for ______ or latex agglutination for _____, and the remainder is inoculated onto media.

Answer 55

India ink preparation | Cryptococcus

Question 56

If more than ___ is submitted, the CSF may be filtered through a membrane filter and portions of the filter placed on media.

Answer 56

5 mL

Question 57

Use of media with antimicrobial agents should not be needed because ____ is normally sterile.

Answer 57

CSF

Question 58

Abscess Fluid, Wound Exudates, and Tissue Using a dissecting microscope, abscess fluid and exudate from wounds can be examined for the______. If _______are present, the material may be plated directly onto the media. Tissue should be _____ before inoculation

Answer 58

presence of granules no granules gently minced

Question 59

______ of tissue has been recommended, but this process might destroy fragile fungal elements, particularly if a zygomycete is present.

Answer 59

Grinding

Question 60

When large sections of tissue are submitted, suspicious areas, such as__________, are selected for mincing and grinding before subsequent culture.

Answer 60

purulent or discolored sections

Question 61

Respiratory specimens Because many fungal infections have a primary focus in the lungs, _________(e.g., sputum, transtracheal aspirates) and ___________ are commonly submitted.

Answer 61

lower respiratory tract secretions | pleural lavage fluids

Question 62

Respiratory Specimens Patients should obtain ___ from a deep cough shortly after arising in the morning. All sputum specimens should be collected in a ______

Answer 62

sputa | sterile, screw-top container.

Question 63

______is easily diagnosed with direct smear and culture.

Answer 63

Oropharyngeal candidiasis

Question 64

________ obtained surgically can be plated directly to media containing antimicrobial agents except for cycloheximide, which can inhibit some fungi.

Answer 64

Nasal sinus specimens

Question 65

Laboratory scientists often receive __________ as specimens for bacteriological culture; on occasion, these specimens grow a yeast that requires identification.

Answer 65

urine, feces, and vaginal secretions

Question 66

Urogenital and Fecal Specimens _____ submitted specifically for fungal culture should be centrifuged and the sediment used to make smears for microscopic examination and to inoculate media. A ________ specimen is preferred.

Answer 66

Urine | first morning voided urine